Population characteristics ofDendrolims superans in Daxing’an Mountains

Dendrolims superans produced one generation every two years. Large larvae and small larvae exist at the same time. It broke out in Daxiang an Mountains in 1990, and seriously destroyed growth ofLarix gmelini Rupr. In order to controlD superans, the population properties ofD superans were studied from 1991 to 1992, including sexratio, age distribution, pattern etc.. The sex ratio ofD. superans population is ♀∶♂ − 1.06:L. The larvae age distribution indicates that larvae over 5 instar is less than younger larvae under 4 instar in Yongqing forest farm, but the younger larvae under 4 instar is more than larvae over 5 instar in Hanjiayuanzi Forest Farm. The population ofD. superans in Yongqing Farm has been declining. and mereasing in Hanjiayuanzi. Pupae and eggs are mainly distributed in middle and lower crowns layer of trees respeetively account for 66% and 59.5% of total individuals. The pupae in higher crown layer is lightly regular distribution and clumping distribution middle and lower crowns layer of trees. The eggs in higher crown is light clumping distribution and random in middle and low crown of tree. (Responsible Editor: Zhu Hong)     

Effects of gamma radiation on the Mediterranean flour moth, <Emphasis Type="Italic">Ephestia kuehniella</Emphasis>, eggs and acceptability of irradiated eggs by <Emphasis Type="Italic">Trichogramma cacoeciae</Emphasis> females

The sensitivity of the Mediterranean flour moth, Ephestia kuehniella, eggs in different stages of development to gamma irradiation was studied and the acceptability of irradiated eggs by Trichogramma cacoeciae females was examined. Eggs ranging in age from 1–24 to 49–72 h were exposed, at 24 h intervals, to gamma radiation dosages ranging from 25 to 400 Gy and effects of gamma radiation on egg hatch and adult emergence was investigated. In addition, the developmental rate of immature stages (larvae and pupae), resulting from irradiated eggs, to the adult stage was examined and the acceptance of irradiated eggs to T. cacoeciae females was evaluated. Results showed that the radio-sensitivity of E. kuehniella eggs decreased with increasing age. Egg hatch in 1–24-h-old eggs was significantly affected at 25 Gy dose and at 75 Gy dose, no egg hatch was observed. When irradiating 25–48-h-old eggs, however, egg hatch was less than 5% at 100 Gy dose, and eggs 49–72-h-old were more resistant; 50 Gy had no significant effect on egg hatch and 300 Gy did not completely prevent it. Irradiation also negatively affected survival to the adult stage. When 25–48-h-old eggs were irradiated, survival to the adult stage was completely prevented at 75 Gy dose and no survival was observed beyond 100 Gy dose in 49–72-h-old eggs. In addition, the rate of development of immature stages resulting from irradiated eggs was negatively affected. While more than 97% of control moths emerged within 30 days, this ratio decreased to 53 and 69% in 1–24 and 25–48-h-old eggs exposed to 25 Gy dose. Furthermore, irradiation positively affected the degree of acceptance of eggs to parasitization; irradiated eggs (≤49-h-old) were more acceptable to T. cacoeciae than cold-treated ones.     

Untersuchungen über Falterabundanzen des Bekreuzten TraubenwicklersLobesia botrana Schiff. im Weinbau

Zusammenfassung Im Jahr 1994 wurde eine bereits 1993 entwickelte und erprobte Fangvorrichtung eingesetzt, um Fragen zu Populationsdichtebewegungen beiL. botrana zu beantworten. Insbesondere wurden Untersuchungen zur Abundanzdynamik und zur absoluten Abundanz von Faltern beider Geschlechter durchgeführt. So konnten Verschiebungen im Geschlechterverhältnis während der Flugperiode nachgewiesen werden. Ursache dieser Geschlechterverschiebung waren unterschiedliche Entwicklungszeiten der Präimaginalstadien bei Männchen und Weibchen. Berechnungen zur absoluten Abundanz von Faltern der 2. Generation ergaben Gesamt-Falterdichten zwischen 33 und 209 Faltern pro 10 m². Die Anzahl der an Trauben abgelegten Eier je Falterweibchen betrug etwa 30. Für das Verhältnis zwischen Falterdichte und Ei- bzw. Larvendichte konnten Korrelationen errechnet werden. Ein Zusammenhang zwischen der ersten und zweiten Generation hinsichtlich des Massenwechsels war nicht feststellbar. Ein vorläufige Bestimmung der kritischen Falterdichte, die im Zusammenhang mit der Anwendung von Pheromonen zur Paarungsstörung von Interesse ist, konnte vorgenommen werden. Sie lag bei maximal 4 männlichen und 4 weiblichen Faltern pro 10 m².

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Investigations on abundances of the grape mothLobesia botrana Schiff. in viticulture

In 1994 a catching device, which had been developed and tested in 1993, was used for answering questions about population density movements inL. botrana. Investigations were focused on abundance dynamics and absolute abundances of moths of both sexes. Movements of the sex ratio are shown. These movements are due to different developmental periods of premature stages of males and females. Calculations on the absolute abundance of moths of the second generation amounted to densities between 33 and 209 moths per 10 m². The number of eggs laid on bunches of grapes equalled approximately 30 per female. The density of moths and densities of eggs and larvae correlated. Densities of first generation larval populations and second generation moths populations of the pest showed no correlation. A temporary determination of the critical density of moths, which is important for the application of pheromones in mating disruption, was achieved. The upper limit equalled 4 male and 4 female moths per 10 m².

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Mit 2 Abbildungen und 3 Tabellen     

Untersuchungen über die Eiparasiten (Hym.: Chalcidoidea) der rotgelben Kiefern-BuschhornblattwespeNeodiprion sertifer Geoff. (Hym.: Diprionidae)

IV. Summary 1. Four or five species of egg parasites ofNeodiprion sertifer have been found in central Europe.2.Dipriocampe diprioni is a primary parasite which overwinters as a first instar larva within the host's egg, The larvae complete feeding in early spring and enter an obligatory diapause which lasts until July–August. Under the influence of the parasite, the egg shell of the host turns brownish. The adults emerge from mid-August onward. The univoltine parasite is thus well synchronized with its major host,N. sertifer.3. A second species, or form, ofDipriocampe has been found, the taxonomic status of which is still unresolved. It is here referred to asDipriocampe sp. forma ignorata. Although not yet separable fromD. diprioni morphologically, its biology is quite different. The larvae mature before the winter and the adults emerge in April–May of the following year, being dependent on alternate hosts. This form is exceedingly rare in lowland areas but possibly common at high altitudes. It remains to be seen whether it is a separate species or a polymorphic, non-diapausing form ofD. diprioni. Host eggs attacked byDipriocampe sp.forma ignorata turn blackish.4. Two species ofAchrysocharella have been found,A. ruforum andA. ovulorum. In lowland areas,Achrysocharella spp. attack the eggs ofN. sertifer in a hyperparasitic capacity, developing at the expense of the larvae and pupae ofDipriocampe spp. or of larvae and pupae of their own kind. There are two or three such hyperparasitic generations during the summer, the last entering hibernation before the new eggs ofN. sertifer make their appearance, thus failing to attack them in a primary capacity.In mountainous areas, where the eggs ofN. sertifer appear earlier,Achrysocharella spp. pass the first generation as primary parasites in the sawfly eggs, and the second (summer) generation as hyperparasites of larvae and pupae ofDipriocampe spp. or of larvae and pupae of their own kind.5.Tetrastichus oophagus has been associated with the eggs ofN. sertifer in a few cases only, but has been more common as a parasite of the eggs ofDiprion pini.6. The importance of the egg parasites ofN. sertifer has to date been underestimated. Egg parasitism is apparently density-dependent and can reach high values during, and immediately after, the break-down of the sawfly populations.     

Maintaining <Emphasis Type="Italic">Bactrocera oleae</Emphasis> (Gmelin.) (Diptera: Tephritidae) colony on its natural host in the laboratory

The olive fruit fly, Bactrocera oleae (Gmelin.) (Diptera:Tephritidae) is a pest on olives (Olea europea) in the Mediterranean basin. An olive fruit fly colony was maintained on olives at 24 ± 1°C, 60% RH, and 16:8 h (light:dark) photoperiod with fluorescent lighting. We investigated oviposition behavior, developmental duration and weights of the biological stages, and adult longevity. A single female laid an average of 19 eggs/day and 200–350 eggs in her lifetime. The maximum number of oviposition stings in a single olive was 156.0 ± 5.77, and 28.00 ± 3.62 larvae out of it completed their development, all pupated, and all emergence successfully. Although the development period was similar for larvae and pupae, adult longevity varied. Male and female emergence percentages ranged as 38.7–52.8, and 32–39.9%, respectively. The results are presented in relation to published studies on olive fruit fly rearing.     

Über Schlupfwespen als Parasiten der Fliedermotte,Gracilaria syringella F. (Lep., Gracilariidae)

On Hymenoptera parasitizing the Syringia Moth, Gracilaria syringella F. (Lep., Gracilariidae)During an outbreak ofG. syringella onFraxinus excelsior in 1973 and 1974 near Munich 12 species of Hymenoptera parasitized the larvae if this pest. There were 3 chief parasite spezies;Apanteles gracilariae Wilk.,A. dilectus (Hol.) andTeleopterus sp. (probablyT. erkias Walk.) which came to nearly 90% of the whole population of parasites in each of the 4 host generations. The whole parasitization of theG. syringella larvae amounted to 12,5% (1973, 2. gen.) ot 31,2% (1973, 1.gen). Teleopterus sp. deposites the eggs int those of the moth and the full grown parasites larvae leave the young host larvae (L₂) within the leaf mines. The two species os genus Apanteles deposite their eggs in the mining larvae and their full grown larvae leave the old host larvae within the leaf rolls.     

Zur Lebensgeschichte und Epidemiologie der GetreidemotteSitotroga cerealella Oliv

Zusammenfassung Die GetreidemotteSitotroga cerealella Oliv. entwickelt in der pal?stinensischen Küstenzone j?hrlich 5–6 Generationen. Der Entwicklungsnullpunkt liegt bei 10,3° C, die Thermalkonstante betr?gt 474°. Die Eizahl schwankt zwischen 80 und 180 pro ♀, die Verteilung der Geschlechter ist wie 1∶1. W?hrend das Entwicklungspotential einesSitotroga-P?rchens bei 6 Generationen in einem Jahr über 30 Milliarden Motten betragen mü?te, betr?gt die tats?chliche Nachkommenziffer eines P?rchens im Laufe eines Jahres unter den klimatischen Bedingungen der pal?stinensischen Küstenebene nur 400–450 Motten. Durch die extremen Temperaturen im Winter und Sommer wird die Zahl der Tiere derart reduziert, da? ihre Zahl im neuen Jahr von der des Vorjahres nicht sehr variiert. Mit 2 Abbildungen     

榆少锤角叶蜂的研究

榆少锤角叶蜂是严重危害榔榆、白榆叶片的新害虫。该虫１ａ发生１代，老熟幼虫钻入杂灌草丛根际或疏松浅土层中结茧，以预蛹越冬。翌年３月下旬化蛹，４月上旬羽化交尾交卵，幼虫期为３２．７８±２．２７ｄ，每头幼虫平均取食量为２５９０３．８３±６７７８．５５ｍｍ２，５月下旬相继老熟下树结茧过夏越冬。成虫产卵主要在低矮小树或大树下层枝条叶片上。该虫体表光滑裸露，抗药性弱，只要防治时机恰当，一般农药均可取得良好效果。以５％氯氰菊脂、２．５％敌杀死１∶３０００或８０％敌敌畏、９０％晶体积敌百虫１∶８００为佳。     

Development,life history characteristics and behaviour of mealybug predator, <Emphasis Type="Italic">Spalgis epius</Emphasis> (Westwood) (Lepidoptera: Lycaenidae) on <Emphasis Type="Italic">Planococcus citri</Emphasis> (Risso) (Homoptera: Pseudococcidae)

The development of immature stages, life history and behaviour of mealybug predator, Spalgis epius (Westwood) (Lepidoptera: Lycaenidae) reared on mealybugs, Planococcus citri (Risso) (Homoptera: Pseudococcidae) was studied in the laboratory. Larvae of S. epius are a potential predator of different species of mealybugs in India. The predator completed its life cycle in 23.8 days with four larval instars. Mean incubation period of egg was 3.9 days. Mean duration of development of larval stages, prepupa and pupa was 9.4, 0.9 and 9.5 days, respectively. The first and last instar larvae measured 1.9 and 11.4 mm in length, respectively. Length and width were not significantly correlated in larvae. Head capsule width was not significantly correlated with larval length in any instar. The female-to-male sex ratio was 1.45:1. Adults were ready for mating one day after eclosion. The pairs remained in copula on an average of 61.3 min. The gravid female contained 74.6 eggs in the ovaries. Unfed butterflies (both males and females) lived 3–4 days, significantly shorter than those with access to water (6–7 days). The results of this study will be useful to utilize the predator as a biocontrol agent.     

Life circle and bionomics ofLymantria dispar L.

The life circle and bionomics ofLymantria dispar was studied from the May to the July of 1997 in Tulihe Forestry Enterprise of Inner Mongolia. The results showed thatL. dispar has one generation in a year, larvae overwinters in eggs, and last 50 days to grow up. From the completing of larvae period to the appearing of adults lasts 11 days. The study made a basis for the period forecasting of L.dispar in Inner Mongolia.     

Biomass of fine and small roots in two Japanese black pine stands of different ages

The biomass and the spatial distribution of fine and small roots were studied in two Japanese black pine (Pinus thunbergii Parl.) stands growing on a sandy soil. More biomass of fine and small roots was found in the 17-year-old than in the 40-year-old stand. There were 62 g m⁻² of fine roots and 56 g m⁻² of small roots in the older stand, which represented mean values of 608 g for fine and 552 g for small roots per tree, respectively. In the younger stand, a total of 85 g m⁻² of fine roots and 66 g m⁻² of small roots were determined, representing a mean of 238 g for fine and 186 g for small roots per tree, respectively. Fine and small root biomasses decreased linearly with a soil depth of 0–50 cm in the older stand. In the younger stand, the fine and small roots developed only up to a depth of 30 cm. Horizontal distributions (with regard to distance from a tree) of both root groups were homogeneous. A positive correlation in the amount of biomass of fine and small roots per m² relative to tree size was found. Fine and small root biomasses increased consistently from April to July in both stands. The results also indicated earlier growth activity of the fine roots than small roots at the beginning of the growing season. The seasonal increases in fine and small root biomasses were slightly higher in the younger stand than the older stand.     

Fumigant and repellent activities of essential oil from <Emphasis Type="Italic">Coriandrum sativum</Emphasis> (L.) (Apiaceae) against red flour beetle <Emphasis Type="Italic">Tribolium castaneum</Emphasis> (Herbst) (Coleoptera: Tenebrionidae)

The biological activity of essential oil extracted from coriander, Coriandrum sativum L. (Apiaceae) against eggs, larvae and adults of Tribolium castaneum (Herbst) was investigated in a series of laboratory experiments. Bioassays conducted in air-tight glass chambers showed vapour toxicity and strong repellency on filter paper arena test towards all the stages used. Responses varied significantly (P < 0.001) within insect stages, dosages and exposures. At 12.0 μg/ml dosage, mortality of adults reached 95%, but for 12-, 14- and 16-days larvae, mortalities were 65, 74 and 82%, respectively. On the developmental inhibition, individuals fumigated at the larval stage confirmed that the percentage of larvae reaching to pupal stage and pupae to adult stage, decreased significantly (P < 0.001) with increasing dosage concentration. The oil fumigation yielded 100% mortality for T. castaneum larvae, pupae and adults at 0.08 μg/ml dosage. The oil had fumigant activity against eggs and the toxicity progressively increased with increased exposure times and concentrations. One hundred per cent T. castaneum egg mortalities were obtained with oil fumigation at 20 μg/ml and 96 h exposure period. C. sativum oil also showed highly repellent activity to the adults of T. castaneum, with overall repellency was 90% and at a dosage of 12 μg/ml repellency was 100% in a filter-paper arena test.     

Biological effects of the entomopathogenic fungus,Beauveria bassiana on the potato tuber mothPhthorimaea operculella (Seller)

A series of investigations have been carried out on the effect of the entomopathogenic fungusBeauveria bassiana on the various developmental stages ofPhthorimaea operculella. Both first and second insatar larvae were more susceptible than the third or fourth instars. The infected prepupae and pupae resulted in marked decrease in the emergence, longevity of moths, deposited eggs and their egg hatchability. An obvious increase in the pupal duration was observed and the resulting malformed adults were also recorded. The latent effects were markedly obvious, specially in high doses ofBeauveria bassiana.     

First results on synchrony between seasonal pattern of pheromone trap captures of cotton bollworm, <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> and appearance of freshly emerged larvae on developing cobs of corn hybrids

Synchrony between development of five corn hybrid varieties of various seasonal growing rates (FAO numbers), seasonal flight pattern of male cotton bollworm, Helicoverpa armigera Hb. (Lepidoptera: Noctuidae), as monitored by pheromone traps, and the subsequent appearance of newly hatched larvae on developing cobs were studied at Mezőhegyes, South-Hungary, in 2003 and 2004. The phenological stages of corn hybrids were evaluated using the Iowa State University Scale (R₁–R₅), the flight of male moths was monitored by large capacity, funnel type of pheromone traps and the appearance of freshly hatched larvae on developing cobs were counted by visual inspection. The synchrony between the flight peak of male moths and the peak apperance of L₁ larvae on cobs was investigated by cross-correlation. In 2003 (average daily temperatures 20.7°C, average daily relative humidity 59.9% for the period of 4–18 July) “DK 391”, “DK 443” and “Maraton” hybrid varieties already reached silking stage (R₁) by the time when pheromone traps indicated a peak, at 7 July (peak capture at 3-day intervals 755.5 males/traps). The number of L₁ larvae peaked on developing cobs of these varieties also at 7 July (7.0, 4.0 and 3.8 larvae/50 cobs, respectively). The synchrony between the flight peak of male moths and the peak appearance of L₁ larvae on cobs was proven (LAG = 0). A rather similar trend was observed in “Vilma” hybrid variety: it reached R₁ stage at 7 July, and L₁ larvae appeared only a few days later (11 July, 3.8 larvae/50 cobs) (LAG = −1). However, “Maxima” hybrid variety reached R₁ stage 1 week later (14 July) than the time of peak captures. Here L₁ larvae peaked as late as at 18 July (0.8 larvae/50 cobs), i.e., only after the cob had reached R₁ stage (LAG = −3). A reverse order of dates of R₁ stage and peak capture was observed in “Maxima” in 2004 (average daily temperatures; 22.5°C, average daily relative humidities 72.6% for the period of 15 July–6 August): it reached R₁ stage at 19 July, while peak trap captures were recorded at 6 August (peak capture at 3-day intervals 20.5 males/traps). L₁ larvae were found in the highest numbers on 2 August (1.5 larvae/50 cobs), practically in synchrony with peak caputres (LAG = 0). “Káma” reached R₁ stage in 16 July, and L₁ larvae peaked at 2 August (1.3 larvae/50 cobs) (LAG = 0). On the rest of the corn varieties larvae were found only in too numbers for performing statistical analysis. We conclude that in order to predict the appearance of L₁ larvae, the phenological stage of the corn variety and the seasonal flight pattern of moths, as measured by large capacity pheromone traps, should be considered in combination. If the corn variety already reached R₁ stage, L₁ larvae appear on cobs as early as the time of peak flight of moths. However, no young larvae appear on cobs despite of high trap captures, until the corn reaches the R₁ stage. These findings are discussed in the view of specifying optimal timing of a pesticide application.     

Nitrogen-fixation dynamics in a cut-and-carry silvopastoral system in the subhumid conditions of Guadeloupe, French Antilles

This paper summarizes several studies on N recycling in a tropical silvopastoral system for assessing the ability of the system to increase soil fertility and insure sustainability. We analyzed the N₂ fixation pattern of the woody legume component (Gliricidia sepium), estimated the recycling rate of the fixed N in the soil, and measured N outputs in tree pruning and cut grass (Dichanthium aristatum). With this information, we estimated the N balance of the silvopastoral system at the plot scale. The studies were conducted in an 11-year-old silvopastoral plot established by planting G. sepium cuttings at 0.3 m × 2 m spacing in natural grassland. The plot was managed as a cut-and-carry system where all the tree pruning residues (every 2-4 months) and cut grass (every 40-50 days) were removed and animals were excluded. No N fertilizer was applied. Dinitrogen fixation, as estimated by the ¹⁵N natural abundance method, ranged from 60-90% of the total N in aboveground tree biomass depending on season. On average, 76% of the N exports from the plot in tree pruning (194 kg [N] ha^–1 yr^–1) originated from N₂ fixation. Grass production averaged 13 Mg ha^–1 yr^–1 and N export in cut grass was 195 kg [N] ha^–1 yr^–1. The total N fixed by G. sepium, as estimated from the tree and grass N exports and the increase in soil N content, was about 555 kg [N] ha^–1 yr^–1. Carbon sequestration averaged 1.9 Mg [C] ha^–1 yr^–1 and soil organic N in the 0-0.2 m layer increased at a rate of 166 kg [N] ha^–1 yr^–1, corresponding to 30% of N₂ fixation by the tree. Nitrogen released in nodule turnover (10 kg [N] ha^–1 yr^–1) and litter decomposition (40 kg [N] ha^–1 yr^–1) contributed slightly to this increase, and most of the recycled N came from the turnover or the activity of other below-ground tree biomass than nodules. This revised version was published online in June 2006 with corrections to the Cover Date.     

Nahrungsaufnahme und Natalität bei palaearktischen Simuliiden (Diptera) 1. Blutfütterung vonBoophthora erythrocephala De Geer 1776 undWilhelmia lineata Meigen 1804 am Kaninchen

Zusammenfassung Während mehrer r Monate wurden Weibchen vonBoophthora erythrocephala undWilhelmia lineata am Kaninchenohr gefüttert und die Überlebensrate während der Eireifungsphase,

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Nutrition and Reproduction in Palaearctic Blackflies (Simuliidae: Diptera). I. Bloodfeeding ofBoophthora erythrocephala De Geer andWilhelmia lineata Meigen on RabbitsFemales of the mammalophilic species,Boophthora erythrocephala andWilhelmia lineata, feed on cattle and horses in the field. When fed on the rabbit's ear under laboratory conditions, they differ considerably in bloodsucking activity, in mortality during digestion of blood, natality, and hatching rates of first instar larvae. InB. erythrocephala 641 wild-caught- fed in 74,1% without seasonal variation. When females were kept up to four days before feeding their bloodsucking activity did not decrease. Laboratory-emerged- usually fed in even higher rates (416/533) and 4–6 days old flies fed more frequently than younger or older females. Survival rates during digestion of blood in 4 days were 60% in wild-caught, 40% in laboratory-emerged-, and 74% in cattle-fed-. Only 29% of wild-caught and the cattle-fed- but 50% of the laboratory-emerged flies could be induced to lay eggs on wet substrate. Natality of cattle- (219 eggs/) and laboratory-emerged fed on the rabbit (225 eggs/) were significantly higher than in wild-caught rabbit-fed- (191 eggs/). The number of eggs developing to first instar larvae generally was low (42%). InW. lineata wild-caught- fed less successfully (162/407) and showed considerable seasonal variation. The best results were obtained in September and October. Keeping them in the laboratory for 1–4 days reduced the bloodsucking activity. In laboratory-emerged- the best feeding result (347/724) were obtained with 4–6 day old flies but their survival during maturation of eggs remained low (55%). It was higher with wild-caught (67%) and cattle-fed- (78%). In all cases 60% of them could be induced to oviposit. The rabbit-fed wildcaught or laboratory-emerged flies produced significantly more eggs (183 resp. 197 eggs/) than cattle-fed ones (138 eggs/). Most egg batches contained only 16% fertilized eggs. In laboratory-emerged- ofB. erythrocephala andW. lineata the potential natality was highest in spring, lowest in summer and increased again in autumn. The number of eggs/ was affected by the blood volume. Starting with laboratory-emerged flies fed on the rabbit a production factor of 10.9 is calculated forB. erythrocephala and of 5.4 forW. lineata rearing from the imago to the first instar larva. When the larvae are reated to adults with 44% efficiency a reproduction of 2.4 resp. 1.2 per generation of females results.

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Mit 4 Abbildungen und 4 Tabellen     

Effect of damaged pine needles on growth and development of pine caterpillar larvae

Chinese pine caterpillar (Dendrolimus tabulaeformis) larvae were fed with pine needles of different degrees of damage to evaluate the effects of pine needles on the growth and development of larvae. The results showed that the nutritional index of the larvae declines after feeding on the damaged pine needlings. The lowest amount of food ingested and voided feces, the lowest nutritional index, slowest development, lightest pupae and most mortality were found in those pine caterpillar larvae fed with pine needles which were 50% damaged. The damaged pine needles significantly affected the population dynamics of Chinese pine caterpillars. The nutritional indices of larvae fed with 25% and 75% damaged pine needles were similar. The nutritional index of the dark morphs was higher than that of the tinted morphs, however, their mortality was lower than that of the tinted morphs. This phenomenon was reversed at the later stage of development when the larvae were fed on 50% damaged pine needles. __________ Translated from Journal of Beijing Forestry University, 2005, 27(6): 83–88 [译自: 北京林业大学学报, 2005, 27(6): 83–88]     

Breeding performance of the second generation in some bivoltine populations of <Emphasis Type="Italic">Ips typographus</Emphasis> (Coleoptera Curculionidae) in the south-eastern Alps

The spruce bark beetle, Ips typographus, is one of the most extensively studied European forest pests. Gaps exist in the knowledge about second generation breeding performance in bivoltine populations. In this study, the breeding performance of the second generation was evaluated in three bivoltine populations of I. typographus in the SE Alps. Length of the maternal galleries (from 40.5 to 44.8 mm), population growth rate (PGR; from 0.7 to 3.6), and emerged adults per m² (from 669 to 1,570 insects/m²) varied among populations and were negatively correlated with bark colonisation density. Pheromone traps set up in the three investigated forests differed in the number of trapped beetles, with mean captures ranging between 5,310 and 19,850 insects per trap. The populations giving the highest captures in the traps showed the lowest bark colonisation density (248 vs. 489 maternal galleries per m²) and the best breeding performance. The populations of parasitoids and predators corresponded to just 1–9 and 2–10% of the emerging I. typographus adults, respectively, and phloem temperature never reached thresholds lethal to I. typographus. Interspecific competition was negligible, whereas intraspecific competition was found to be the main factor affecting the breeding performance of the second generation, although with different intensity according to the colonisation density. It is hypothesised that competition with the first generation and spring precipitation influence the number of suitable hosts available to the second generation.     

Effect of adult nutrition and insect density on the performance of spotted stem borer, <Emphasis Type="Italic">Chilo partellus</Emphasis> in laboratory cultures

The spotted stem borer, Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) is being successfully reared on artificial diets for screening programmes. Besides quality characteristics of the diet, rearing density and adult nutrition have significant implications on the successful mass multiplication of lepidopterans. The performance of C. partellus moths was assessed on different adult diets (water and sugar solution) and compared with unfed adults. Further, three pairing densities, viz. 2, 5 and 8 pairs/oviposition jar (1177.5 cm³) were compared for their effect on C. partellus longevity and fecundity. In another experiment, different larval densities (100, 150 and 200 neonate larvae/diet jar) were evaluated for their effect on the larval survival. Water-fed moths (both males and females) lived longer (7.32 and 7.26 days, respectively) and showed higher fecundity (307.17 eggs) than the sugar-fed or unfed moths. The latter, however, showed better egg hatchability (76.55%) than the water- or sugar-fed moths (60.45 and 50.59%, respectively). The longevity (5.67 days) and fecundity (258.46 eggs) were significantly greater at pairing density of 2 pairs/jar. The larval survival was higher (58.50%) at rearing density of 100 larvae/jar. The neonate larval release into diet jars was compared with conventional egg release and both modes were no different with respect to larval survival.     

Soil biological properties under different tree based traditional agroforestry systems in a semi-arid region of Rajasthan,India

An investigation was carried out in an Entisol at farmers’ field in Jaipur district, Rajasthan, India during 2002–2004 to evaluate the effect of traditionally grown trees on soil biological characteristics. Traditionally grown trees in farm lands for study consisted of Prosopis cineraria (L.), Dalbergia sissoo (Roxb.) ex DC, Acacia leucophloea (Roxb.) and Acacia nilotica (L.) Del. having a canopy diameter of 8 m. Results revealed significant and substantial improvement in soil biological activity in terms of microbial biomass C, N and P, dehydrogenase and alkaline phosphatase activity under different tree based agroforestry systems as compared to a no tree control (cropping alone). Soil microbial biomass C, N and P under agroforestry varied between 262–320, 32.1–42.4 and 11.6–15.6 μg g⁻¹ soil, respectively, with corresponding microbial biomass C, N and P of 186, 23.2 and 8.4 μg g⁻¹ soil under a no tree control. Fluxes of C, N and P through microbial biomass were also significantly higher in P. cineraria based land use system followed by D. sissoo, A. leucophloea and Acacia nilotica in comparison to a no tree control. Thus, it is concluded that agroforestry system at farmers’ field enhance soil biological activity and amongst trees, P. cineraria based system brought maximum and significant improvement in soil biological activity.